Wouldn't MP-12 (or MP-12+) work just fine for this? Skyfire/Jetfire has some "size inconsistencies" during his original cartoon appearances. Mass shifting, bad animation, forcing different toy lines into a single cartoon, call it what you will. The supposed mini-figs would be scaled to drive up Jetfire's alt-mode ramp and into the plane. That would make them the size to fit into Skyfire's hand. Comparing bot modes, you'll need a MP-12 bot for MP-Jetfire to be able to re-create that scene. Those alt mode sizes are all over the place. I'm much happier that they make the bots scale properly rather than the alt-modes. A real F-15 versus a tractor trailer matching in alt-mode would put Starscream 2 or 3 times taller than Optimus Prime in bot-mode.